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June, 1911 engines previously mentioned, and structurally along very similar lines. They all labcr under the disadvantage that a lamp is required 'for starting and that a period of time variously estimated at from ten to thirty min- utes is consumed in preliminary heat- ing of the combustion chamber or bulb. Marine Kerosene Engines. Similar engines have been devel- oped on the continent of Europe and to a certain extent in this country. The demand for such engines here has not been great enough as yet to produce many or much, while in Ger- many and surrounding countries a more. promising solution has present- ed itself. The great success of the Diesel oil engine in stationary work had 'its influence here just as the hot bulb stationary engine of England _in- fluenced development there. With the recent expiration of the Diesel patents firms in western and central Europe have become free to develop this type at will and some really mar- vellous work has been done along ma- rine lines. Both the hot bulb and the Diesel type have been built to operate on the two stroke and four stroke cycles but unlike the former the Diesel en- gine has been built double acting and in »sizes. up. to 1,500, Hun) oper: umit with 2,000 H. P, in sight. The Diesel Marine Engine. The Diesel marine type is multi- cylindered like the others and in many examples very closely resembles them in general appearance, though there is a tendency in evidence to give them more and more the appear- ance of the reciprocating steam en- gine in many respects. This engine has the great advantage that because of the cycle upon which it operates it is possible to obtain greater power per cubic foot of pis- ton displacement with it than with any other internal combustion engine, and for the same reason this engine can handle much less volatile and hence much cheaper fuel than the other liquid fuel engines. All these oil engines were first made non-reversible, backing being effected by means of reversing gears or reversing propellers. Within the last few years however, some few builders have succeeded in making hot bulb engines reversible and practically all the larger Diesel engines now constructed are reversible and direct connected to the propeller. Before closing this brief review of liquid fuel internal combustion marine engines it should be mentioned that "'TAE MarRINeE REVIEW at least one American builder has constructed and installed double acting gasoline marine engines giving 300 He P. "per "six cylinder unit): Moré than this these engines are perfectly reversible and are direct connected to the screw. The development of internal com- bustion marine engines using gaseous fuels has not yet proceeded to the same extent as that of the engines already reviewed. The reason for this is that until the gas producer was made a commercial possibility there was no way of obtaining an adequate cheap supply of gas fuel on ship board. As a matter of fact the de- velopment of the gas producer for stationary work has hardly yet pro- gressed to such a point that those concerned in its evolution and _ its successful future are satisfied that they have reached what may be call- ed stable conditions. Many things connected with the practical opera- tion of producers indicate the de- sirability. of further research and further modification with the object of making it a more flexible, more reliable, and more efficient apparatus. Marine Gas Producer. The marine gas producer may be said to be non-existent at the present time. To be sure, quite a number of producers have been installed in ves- 'sels and have given satisfactory re- sults; but «mest, ai-<not all; of them are capable of handling coal of low volatile content only, are of small capacity, and involve the use of ab- normally bulky cleaning apparatus. Most of these producers have been merely stationary types installed aboard ship and are no more a solu- tion of the marine gas problem than was the installation in connection with one of them of a_ horizontal double opposed gas engine by one of the prominent buiiders of Europe. Some few producers have been de- signed and installed with the pecul- iar requirements of marine condi- tions in view but none of them have been more than acceptably success- ful and none of them seem to indi- cate the direction of the final solu- tion. In this state of the art the largest plant which one could install with a moderate degree of certainty of suc- cessful operation is probably one de- veloping about 1,000 to 1,500 H. P. and this would probably call for two or even three producers. Each would have to have its clumsy and space- cecupying cleaning apparatus. There would probably have to be at least _bustion tor 209 two engine units, each having from four to six cylinders. This would be little more than a stationary plant, modified to meet marine requirements to the limited extent which our present inadequate knowledge would permit. It could be made to operate on either anthra- cite or bituminous coal but would be bulky and costly. Most of the marine producer gas engines 'already installed have been built for rotation in one direction only and were capable of operating only through a very limited range of speeds.' Backing, "and {0 =a certain extent much of the maneuvering, has been eitected through reversing gears, electrical connection or _ reversible propellers. These engines have all been single acting and most, if not all, operated on the four stroke Otto cycle. Inherent Advantages and Disadvan- tages of Internal Combustion for Marine Propulsion. With this brief review of the de- velopment of the art and in the light of the requirements of marine oper- ation we may now discuss the relative merits and demerits of internal com- marine propulsion. It will be noted as this discussion pro- cceds that 'some | of. the points in favor of this method of propulsion and some of those opposed to it are inherent in the nature of the work- ing process and may not therefore be eliminated though they may be much modified, for good or for bad, by the excellence of the design in any particular case. The points in question may be enumerated as follows: (a) The internal combustion en- gine is much more sensitive to mal- adjustment than either the reciprocat- ing steam engine' or the steam tur- bine. This. weakness is characteristic of the working process and while it may be minimized by careful design, by the duplication of certain small auxiliaries, by careful attention dur- ing operation, and such, it is bound to remain to a certain extent. It ensues largely from two facts. First, in internal combustion engines of all kinds the process carried out for the production of power is largely chemical, in contrast to that of the steam engine which is almost en- tirely physical. The conditions un- der which the necessary chemical processes can be made to take place are much more limited than those which govern the occurrence of the physical phenomena connected wit\